Question: For a given input value $v$, the function $f$ outputs a value $u$ to satisfy the following equation. $u-5=-4(v-1)$ Write a formula for $f(v)$ in terms of $v$. $f(v)=$
Answer: $f(v)$ expresses $u$ as a function of $v$. To arrive at a correct formula, all we have to do is solve the equation for $u$. $ \begin{aligned}u-5&=-4(v-1)\\\\ u&=-4(v-1)+5\\\\ u&=-4v+9\end{aligned}$ Therefore, this formula expresses $u$ as a function of $v$ : $ f(v)=-4v+9$